1. Field of the Invention
The present invention relates to a copying system, including a copier and a document feeder, in general and more particularly to the control of document feeders which feed original documents onto the document platen of the copier.
2. Prior Art
The use of reproduction machines such as copiers for reproducing copies of original documents is well known in the prior art. A typical copier includes a document platen and a plurality of processing stations. The document platen is adapted to receive an original document while the processing stations form and generate one or more copies of the original document.
Documents are registered, that is presented on the document platen either automatically or manually. For automatic presentation, a document feeder places the document on the document platen. After copying, the document is transported to a receiving tray. For manual presentation, the document is registered by hand on the document platen. After copying, the document is removed.
In order to register the documents on the platen, a gating mechanism is disposed relative to the platen. Proper registration is necessary to assure that a latent image of the entire document falls on the working area of the photoconductive surface. To this end, one edge of the document is usually aligned with the registration gate.
Most copying systems operate either in the automatic mode or the manual mode. In the automatic mode, the gating assembly and document registration are automatically controlled. In the manual mode, the gating assembly and document registration are manually controlled. Usually an operator positions the gating assembly relative to the document platen. Oftentimes the operator fails to remove the gating assembly from the platen. In the event that the document feeder is used with the gating assembly on the document platen, documents collide against the gating assembly. This usually results in a paper jam and damage to the document.
In the Eastman Kodak Ectoprint 100 Copier, the paper jam problem is solved by activating a manual switch when a manual aligning plate is on the document platen. The copier includes a pivot plate that acts as the document guide for a recirculating automatic document feeder (RADF) when the RADF is in place over the platen and is also pivotable over the platen to establish a reference edge for copying documents manually. The plate consists of a nub on one end which cooperates with a manual switch in the RADF to prevent RADF operation whenever the plate is detected to be in the reference edge establishing position (that is on the document platen).
U.S. Pat. No. 4,170,414 describes a copier having an output sensor for sensing passage of a sheet from a document platen. It includes a movable gate which is automatically activated to allow sheets to be aligned and ejected from the document platen.